Method of and apparatus for forming glass tubes.



' K. KUEPPERS. METHOD OF AND APPARATUS FOR FORMING GLASS TUBES.

APPLICATION FILED SEPT- 9,1913

Patented Apr. 22, 1919.

O Q/O/ 0K1 7 subject of the King of Prussia, residin actate.

Specification of Letters Patent.

Patented Apr. 22, ieie.

application filed fieptember 9, 1913. serial No. 7%,e4t2.

To all whom it may concern: I

Be it known that I, KARL KUEPPERs, a at 58 Hubertus strasse, city ofAachen, ermany, have invented a certain new and useful Improved Methodof and Apparatus for Forming Glass Tubes, of which the following is aspecification.

This invention relates to a method of and apparatus for forming glass orlike easily fusible tubes of any desired longitudinal or transversecross-section such, for example, as cylindrical, conical or irregularlyshaped tubes either'circular, elliptical, angular or of other desiredshape in cross-section.

In order that the invention may be more clearly understood reference ismade to the accompanying drawings whereon Figures 1, 2 and 3 arevertical sections showing'the different stages of manufacture of aconical tube, while Fig. 4 shows the finished conical tube in side view.Figs. 5 and 6 show other forms of tube in side view, while Figs. 7 to 12illustrate various cross-sectional shapes. a

Fig. 13 is a side view illustrating one form of core hereinafterreferred to.

Referring to Fig. 1 of the drawings: 1 designates a glass tube closed atits upper end at 2 and open at its lower end 3. Within this tube isfitted a conical core 4, shown in Figs. 1 to 3 as solid but which may ifdesired be hollow. After inserting the core 4 the glass tube l-is moreor less evacuated and sealed at its lower end 3 as illustrated in Fig.2. The whole arrangement is then gradually heated. The upper end of thetube is heated externally to a red heat for a distance of about a fewcentimeters, so that the annular part thus'heated softens. The tube maybe heated by means of a metal ring 5 through which an electric currentmay be passed so as to heat-up the metal ring, or a coil may be woundthereon and an alternating magnetic field induced thereby or, ifdesired, the ring may be heated by means of gas or the like. Theexternal air then compresses the softened part of the tube against theconical core so that it conforms to the shape thereof. The tube 1 andthe ring; 5 may at the same time be rotated relatively to one another byrotating either the tube 1 or the ring 5, so as to attain uniformheating and softening of the tube. Simultaneously the tube 1 and ring 5are moved relatively to one another in the 1ongi- I after tudinaldirection by raising the tube 1 or lowering the ring 5 so that, theannular softened part moves successively toward the other end of theglass tube, so that the softened part of the glass conforms to the shapeof the core to form a conical tube.

Fig. 2 shows the conical tube nearing com pletion, the tube 1 havingadapted itself to the shape of the core 4 from the upper end down to theposition to which the ring 5 is moved. At the same time as the conicaltube is formed, a downwardly advancing bulge 6 is formed owing to thediminution, of the periphery of the glass tube as it adapts itself tothe shape of the core.

Fig. 3 shows the finished conical tube, the ends of the tube being cutoff after the tube has cooled, whereupon the core 4: may be readilyremoved.

The glass tube may also be heated in the reverse direction, that is tosay, from the narrow end to the wider end, and during this processthetube 1 may be subjected to either compression or tension so as toincrease or reduce the thickness of the tube. The tube may also beheated in longitudinal strips, the strip softened thereby conforming tothe shape of the core and the whole tube being formed byrotating thetube about its axis. The core may also be simultaneously heated or thecore alone may be heated from the exterior by means of an alternatingelectric current or induction current so as to heat-up the core to thedesired temperature through the glass tube. The tube 1 may be 'filledwith 'an inert gas such as carbon diin any suitable manner and mayconsist of any desired material such for example that it must bedestroyed in order to be removed. The whole arrangement, tube and core,may also be heated to softening either before or evacuating. Moreover,mechanical means may be su'bstiturted for the external air pressure, forexample, a rotatable roller arranged immediately behind the heatingdevice or ring 5 so as to press the softened glass against the core. Theannular heating may for example be effected by means of flames,electrical heating elements or alter- I natin or inducing currents'whichdirectly heat t e metal core. For manufacturing in large quantities a,plurality of the tubes and cores may be arranged in devices whlch heatthe tubes over their whole len h until a certain temperature isattained, a though in the case of uniform heating by .means of theheating element 5 in Fig.- 1 a rotation of the tubes 1 is not necessary.The advancing petubes may also be placed in furnaces and slowly heateduntil softened and formed, and then allowed to'cool. In this case thedevice can also be so arra ed that the heat supplied to oneend of thedevice is reater than at the other end and gradua y advances toward thatend. The tubes ma furthermore be arranged parallel to ac other andpassed through an alternating current or induction field, whichpreferably heats the individuaL'tubes uniformly.

Tubes manufactured in the foregoing manner correspond exactly to theshape of the core so that the slightest variation in shape may beproduced such as-dilferences of one-hundredth of a millimeter or more.It is thus possible to simultaneously manufacture tubes engraved in anydesired manner, for example, provided with numbers, names, graduationsor the like. For this purpose the core is graduated or etched in knownmanner. Fig. 13 shows a graduated core in two parts so that it may betaken to pieces. The two halves 4; and4 so that their contiguous faces7-8 are in clined to,the axis of the core.- The two halves 4 and 4:" maybe secured together in any suitable manner, as for example, by means ofscrews. The half 4 is provided with graduations as illustrated in Fig.13. On the completion of the formation of the tube the halves 4 and 4 ofthe core are detached, whereon the half 4" may be pushed beneath thehalf 4", when the latter may be removed from-the tube. It is thuspossible to manufacture measuringdevices such as gage glasses, burettesor the like in lar e quantities with etchings which are exacty similartoeach other. A further modification in the manufacture of such tubescon-' sists in pushing the glass tube over a corresponding core orinserting the'core in the tube, filling the tube with an inert case thecore is liable to oxidation an closing the tube, but not air-tight. Theheatand softening are of waige shape as in horizontally and moving theheating device 5 from one end to the other thereof so that the tubefuses on the core. The tube may also be softened and a core insertedtherein.

It will of course be understood that any desired apparatus may beemployed for carrying out the foregoing methods.

I cla1m:- 1. A process for the production of glass 'tubesof exact innerform and dimensions,

which consists in mounting the tube. on the outside of a suitably shapedmandrel or core of a size and shape corresponding to the size and shapeto be given to thesaid tube, next heating the walls of the glass tubewhile on the mandrel sufliciently to soften the same,-

and while in a softened state, pressing the softened walls inwardly, insuccessive stages lengthwise of the tube, into conformation with saidmandrel or core.

2. A rocess for the production of glass tubes of exact dimensions inlongitudinal and in cross section, which consists in mounting the tubeon a. suitably shaped mandrel or core, and heating and softening thewalls of the glass tube, which is more or less evacuated, said wal'lsbeing then pressed into contact with said mandrel or core by theexternal air pressure.

3. A-process, for the production of glass tubes of exact dimensions inlongitudinal and in cross section, which consists in mounting the tubeon the outside of a suitably shaped mandrebor core, next heating thewalls of the glass tube while on the mandrel, said heating operationbeing started near one end of the tube, and progressively advancingtoward the other end, and progressively pressing the softened glassinwardly into contact with said mandrel or core.

4:. A process for the production of glass tubes of exact dimensions inlongitudinal and in cross section, whlch conslsts 1n mounting the tubeon a suitably shaped mandrel or core, formed in separate sections, andheating and softening the walls of the lass tube, said walls being thenpressed into contact with said mandrel or core, thereafter separatelyremoving the several sections of said mandrel or core.

' 5. A process for'the production of marked in mounting the tube on asuitably shaped mandrel or core having markings thereon,

and divided longitudinally into a plurality of wedge-shaped longitudinalsections, and heating the walls of the glass tube sufficiently to softenthe same, saidgwalls being pressed into contact with'said mandrel orcore while in a softened condition, whereby the markings on the mandrelare imparted to the tube, thereafter separately removing the sections ofsaid mandrel or core.

6. Apparatus for forming lass tubes of any desired longitudinal ortransverse crosssection, comprising a core upon which the tube ismounted said core being of shorter length than the tube to enable theends of the tube to be sealed, and an annular heating element adapted tosurround said tube and movable longitudinally relatively thereto.

7. Apparatus for forming glass tubes of any desired longitudinal ortransverse cross section, comprising a core upon which the tube ismounted said core being of shorter length than the tube toenable theends of the tube to be sealed and an annular heating element adapted tosurround said tube and movable longitudinally and rotatably relativelythereto.

8. The method of forming etched or engraved tubes which consists inmounting a tube upon a correspondingly etched or engraved core,partially evacuating the tube and sealing the latter, and'thereuponheating the tube to softening so that the latter adapts itself to thecore.

9. An apparatus for forming glass tubes, which comprises a mandrel orcore of any desired longitudinal cross section, upon which the tube ismounted, said mandrel being shorter than the tube to enable the ends ofthe tube to be sealed, said mandrel being longitudinally divided intoWedging sections, and markings upon one of said sections, and an annularheating element adapted to surround said tube and movable longitudinallyand rotata'bly relatively thereto. y.

10. Apparatus for forming glass tubes of any desired longitudinal ortransverse crosssection, comprising a suitably shaped man- 49 drel orcore, formed in separable sections upon which the tube is mounted, saidcore being of shorter lengththan the tube to enable the ends of the tubeto be sealed, and means for heating the tube.

11. Apparatus for torming glass tubes of any desired longitudinal ortransverse cross-section, comprising a suitably shaped mandrel or corehaving markings thereon, and divided longitudinally into a, plurality 50of separable parts, upon which the tube is mounted, said core being ofshorter length than the tube to enable the ends of the tube to be sealedand means for heating the tube.

In testimony whereof I have afiixed my signature in presence of twowitnesses.

KARL KUEPPERS.

Witnesses:

CARL LAn'rnR, JEAN GroBBELY.

